Power plants are operated in the most diverse environments and are therefore exposed to the most diverse environmental conditions. The majority of power plants operate within a wide range of environmental conditions and especially of ambient temperatures which depend upon the time of day and the time of year.
According to FIG. 4, in addition to a hall 24 in which a gas turbine unit 10 is accommodated, such a power plant 33 comprises additional buildings 34, 35 and 36 in which other plant sections, office spaces, control equipment or the like are accommodated.
Depending upon the respective environmental conditions, these buildings 34, 35 and 36, depending upon requirement, are heated, ventilated or air conditioned (heating, ventilation, air conditioning—HVAC). In the case of ventilation, the air mass flow which is required for this is open or closed loop controlled by means of frequency-controlled blowers or fans or by means of parallel operation of a greater or lesser number of blowers. In the case of heating, the heating capacity can be open or closed loop controlled. In any case, an HVAC system requires significant additional energy if the ambient temperatures are low or high.
On the other hand, the gas turbine unit 10, which is provided in the power plant 33, generates a significant level of waste heat which has to be discharged to the outside by means of suitable measures.
The schematic diagram of such a gas turbine unit 10 is shown in FIG. 1. The gas turbine unit 10 comprises a gas turbine 14, a diffuser 15 connected downstream, and a generator 16, driven by the gas turbine 14, for generating electric power. The gas turbine 14 draws in fresh air 22 by a compressor 17, compresses this air and discharges the compressed air as combustion air to a combustion chamber 18 where it is used for combusting a fuel 23. The resulting hot gas 20 is expanded in a subsequent turbine 19, performing work, and then enters the diffuser 15 in order to be finally discharged to the outside as exhaust gas 21.
For sound attenuation reasons, there is typically a gas turbine enclosure 11, which encloses the gas turbine 14, a diffuser enclosure 12, which encloses the diffuser 15, and a generator enclosure 13, which encloses the generator 16. In these enclosures 11, 12 and 13, waste heat accumulates during operation and has to be discharged from said enclosures. Corresponding ventilation devices are described in US 2002/0023426 A1, for example. Since the second radial bearing of the gas turbine 14 is arranged in the diffuser, the diffuser enclosure 12 in particular must be well ventilated. Furthermore, attention has to be paid to the fact that an explosion protection has to be provided for the gas turbine enclosure 11, whereas the diffuser enclosure 12 is not subjected to these limitations.
It has already been proposed (WO 01/46565 A1) in the past to use an air conditioning system—which is connected to a cooling circuit—in a power plant for the air conditioning of an operational equipment container, in order to minimize the electric power requirement for the air conditioning system by utilizing the energy which is present in the cooling circuit.
Such a connection between a cooling circuit of the power plant and an air conditioning system of a room located in the power plant is comparatively costly because an air conditioning system is not necessary for the connection. Furthermore, costly installations have to be undertaken in the cooling circuit in order to be able to utilize the energy saving.